| 초록 |
We fabricated improved visible-light ZnO phototransistor via adding solution processed thin Al2O3 layer. The concentration of oxygen vacancies, which generate the photo-excited electron-hole pairs by absorbing visible light, were improved by adding Al2O3 layer at the bottom of ZnO. In addition, it was found that the valence band offset and conduction band offset between the Al2O3 and ZnO was 0.21 and 0.77 eV, respectively. Thus, the photogenerated holes were efficiently separated, contribute the photogating effect, while remaining photoexcited electrons contribute the charge carrier. The Al2O3/ZnO phototransistor showed highly improved photo-response characteristics (photoresponsivity: 292.46 A/W, photosensitivity: 2.31 × 109) than that of ZnO phototransistor (photoresponsivity: 1.01 A/W, photosensitivity: 4.05 × 106) under 520 nm wavelength light exposure. Our results suggest useful way for fabricating visible-light phototransistor using ZnO by adding solution processed Al2O3 layer. |
